Substituted diphenyl



United States atent 3,081,355 SUBSTITUTED DIPH'ENYL Richard L. Johnson, Edwardsvill, Ill., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed May 20, 1960, Ser. No. 30,439 1 Claim. (Cl. 260-613) This invention relates to a novel substituted diphenyl compound useful asa heatand oxidation-stable lubricant and to compositions containing the compound.

In general, several promising types of lubricants which are stable under the elevated temperatures of mllitary and commercial aircraft turbine engines have been found. One important class comprises diesters of alkane dioarboxylic acids; this type of compound is typified by d1-2- ethylhexyl sebacate. Another is the polyphenyl ethers which are represented by such compounds 'as m-bis- (phenoxy)benzene. While both of these types of compounds have worthwhile lubricating properties, both have drawbacks which interfere with their extended use. The diesters are generally too volatile to be useful at temperatures above about 500 F. and begin to decompose at around 600 F. The polyphenyl others, while stable and relatively non-volatile :at these temperatures, have melting points so high that they'are solids at or above room temperature.

It is an object of this invention to provide a novel diphenyl compound having unexpectedly superior lubrieating properties coupled with an unusually low melting point. Another object of the invention is the provision of lubricant compositions containing such a diphenyl compound. Still another object of the invention is the provision of novel low-melting lubricant compositions comprising the novel diphenyl compound of the invention and polyphenyl ethers. Other objects will be apparent from the following discussion of the invention.

These objects are accomplished in the invention by o- (m-phenoxyphenoxy)diphenyl. This compound has the and has a molecular weight of 306 and a melting point of 505 1 C.

To illustrate the superior high-temperature lubricating properties of the compound of the invention, the results of measurements made on this and comparable lubricants are presented in Table I below. The materials selected were those having viscosities on the order of about one centist-oke at 490 F., well within the range regarded as suitable for aircraft gas turbine lubricants.

1 600+r.p.m., 500 F., 50 kg. load, one hour.

Table II Hours to Absorb l Millimole Lubricant Oz/g. Oil (Copper Catalyst) at 400 F.

Inhibited Hercoflex 600 (mixed esters of pentearythritol) 19 o-(m-Phenoxy-phenoxy)diphenyl 122 Because of these desirable properties, the novel diphenyl described may readily be employed both as a lubricant and in admixture with other lubricants. For example, when it is added to another higher melting lubricant, the resulting mixture is characterized by a melting point considerably lower than that of the higher melting component.

The use of such mixtures for melting point reduction has proved of particular interest with diphenyl diphenyl oxides. These compounds are those diphenyl oxides having a phenyl substituent on each of the phenyl rings att-ached to the oxyradical. Of these, the preferred compositions are those wherein the o(m-phenoxy-phenoxy) diphenyl makes up at least about two-third of the total composition on a Weight basis. In Table III are presented the minimum melting points of binary systems containing the novel compound of the invention with the diphenyl oxides noted.

It will be seen from these data that the melting points of the mixtures including the compound of the invention are considerably lower than that of the higher melting component and are about 10 C. lower than the melting point of the lower melting component.

To prepare the o-(m-phenoxyphenoxy)diphenyl, a mixture of m-methoxy-phenyl, potassium hydroxide and bromobenzene was heated in the presence of copper powder. The crude reaction mixture was extracted with benzene and the benzene layer was washed with water and then fractionated under reduced pressure to yield m-methoxydiphenyl ether in yield.

The m-methoxy-dipheny-l ether, -a liquid boiling over the range 167 C./13 mm, was heated in refluxing glacial acetic acid containing 48% hydrobnomic acid for 48 hours. The solution was then extracted with benzene and the benzene solution washed with water and vacuum fractionated. A yield of 80% m-hydroxydiphenyl ether was thus obtained as a light yellow oil boiling over the References Cited in the file of this patent range of 113-155 C./0.3 mm. This compound was melted and converted to the sodium salt by reaction with UNITED STATES PATENTS metallic sodium. The sodium salt was then reacted with 2,263,563 NOV. 25, 1941 2-iodiobiphenyl in the presence of a copper catalyst at 5 2,429,905 Wflght Oct. 28, 1947 atmospheric pressure and 225-315 C. 2,862,034 Hamlln Nov. 25, 1958 The product o-(m-phenoXy-phenoxy)diphenyl was iso- 2,902,518 Hurdls et Sept. 1, 1959 lated from the reaction mixture by benzene extraction fol OTHER REFERENCES lowed by vacuum distillation, It was recrystallized from a hexane/isopropanol mixture to give a 34% yield of the 10 C and April 1959 pages 64 and compound having a melting point of 50-51 C.

I claim as my invention:

0- (m-Phenoxy-phenoxy) diphenyl. 

